Principles and Techniques of Instrument Processing and Sterilization Chapter 21 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights

Principles and Techniques Principles and Techniques of Instrument Processing of Instrument Processing

and Sterilizationand Sterilization

Chapter 21Chapter 21

Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.


Lesson 21.1Lesson 21.1


Learning ObjectivesLearning Objectives

Pronounce, define, and spell the Key Terms.Pronounce, define, and spell the Key Terms. Discuss the seven steps in processing dental Discuss the seven steps in processing dental

instruments.instruments. Describe the classification of instruments Describe the classification of instruments

used to determine the type of processing.used to determine the type of processing. Describe the Centers for Disease Control and Describe the Centers for Disease Control and

Prevention (CDC) guidelines for the Prevention (CDC) guidelines for the sterilization and disinfection of patient-care sterilization and disinfection of patient-care items.items.

(Cont’d)(Cont’d)




Describe the CDC guidelines for cleaning and Describe the CDC guidelines for cleaning and decontaminating instruments.decontaminating instruments.

Explain the purpose of a holding solution. Explain the purpose of a holding solution. Understand the safety precautions necessary in Understand the safety precautions necessary in

the operation of an ultrasonic cleaner.the operation of an ultrasonic cleaner. Describe the precautions necessary in the Describe the precautions necessary in the

packaging of materials for sterilization.packaging of materials for sterilization. Describe the CDC guidelines for the preparation Describe the CDC guidelines for the preparation

and packaging of instruments for sterilization.and packaging of instruments for sterilization.


IntroductionIntroduction

One of the most important responsibilities One of the most important responsibilities of the dental assistant is to process of the dental assistant is to process contaminated instruments for reuse.contaminated instruments for reuse.

Instrument processing involves much Instrument processing involves much more than sterilization.more than sterilization.

SterilizationSterilization is a process intended to kill is a process intended to kill all microorganisms and is the highest all microorganisms and is the highest

level of microbial destruction. level of microbial destruction.


CDC Guidelines for CDC Guidelines for Instrument-processing AreaInstrument-processing Area


Instrument ProcessingInstrument Processing

Instrument processing involves much more Instrument processing involves much more than sterilization. Proper processing of than sterilization. Proper processing of contaminated dental instruments is actually a contaminated dental instruments is actually a seven-step process. seven-step process.

Although the seven steps are not difficult to Although the seven steps are not difficult to learn, it is very important for you to have a learn, it is very important for you to have a clear understanding of how and why each clear understanding of how and why each step is performed.step is performed.


Terms Used in Instrument Terms Used in Instrument ProcessingProcessing


Classification of Patient-Care ItemsClassification of Patient-Care Items

Patient-care items are categorized into three Patient-care items are categorized into three classifications: classifications: CriticalCritical Semicritical Semicritical Noncritical Noncritical



Classification of Patient-Care ItemsClassification of Patient-Care Items


The categories are based on the risk of The categories are based on the risk of infection associated with their intended use.infection associated with their intended use.

The classifications are used to determine the The classifications are used to determine the minimal type of posttreatment processing. minimal type of posttreatment processing.


Critical InstrumentsCritical Instruments

Critical instruments are items used to Critical instruments are items used to penetrate soft tissue or bone. penetrate soft tissue or bone.

They have the greatest risk of transmitting They have the greatest risk of transmitting infection and should be sterilized with the use infection and should be sterilized with the use of heat.of heat.

Examples of critical instruments include Examples of critical instruments include forceps, scalpels, bone chisels, scalers, and forceps, scalpels, bone chisels, scalers, and burs.burs.


Semicritical InstrumentsSemicritical Instruments

Semicritical items instruments touch mucous Semicritical items instruments touch mucous membranes or nonintact skin and have a membranes or nonintact skin and have a lower risk of disease transmission. lower risk of disease transmission.

The majority of semicritical items in dentistry The majority of semicritical items in dentistry are heat-tolerant, and they should also be are heat-tolerant, and they should also be sterilized.sterilized.

If the item will be damaged by heat, it should If the item will be damaged by heat, it should undergo, at a minimum, high-level undergo, at a minimum, high-level disinfection. disinfection.


Noncritical InstrumentsNoncritical Instruments

Noncritical instruments pose the least risk of Noncritical instruments pose the least risk of transmission of infection because they come into transmission of infection because they come into contact only with intact skin, which is an effective contact only with intact skin, which is an effective barrier to microorganisms. barrier to microorganisms.

These items should be cleaned and processed with These items should be cleaned and processed with the use of an EPA-registered intermediate-level or the use of an EPA-registered intermediate-level or low-level disinfectant after each patient use.low-level disinfectant after each patient use.

Noncritical clinical devices include the position Noncritical clinical devices include the position indicator device of the x-ray unit tube head, the lead indicator device of the x-ray unit tube head, the lead apron, and the curing light that comes into contact apron, and the curing light that comes into contact only with intact skin.only with intact skin.


Personal Protective EquipmentPersonal Protective Equipment

For disease agents from a previous patient to For disease agents from a previous patient to be prevented from being transferred to be prevented from being transferred to yourself, another dental-team member, or the yourself, another dental-team member, or the next patient, instrument processing must be next patient, instrument processing must be performed in a consistent and disciplined performed in a consistent and disciplined manner. manner.

You must always use personal protective You must always use personal protective equipment (PPE), including utility gloves, equipment (PPE), including utility gloves, mask, eyewear, and protective clothing, when mask, eyewear, and protective clothing, when processing instruments. processing instruments.


Fig. 21-1 PPE must be worn during preparation of Fig. 21-1 PPE must be worn during preparation of instruments for sterilization.instruments for sterilization.


Transporting and Processing Transporting and Processing Contaminated Patient-Care ItemsContaminated Patient-Care Items

The dental assistant may be exposed to The dental assistant may be exposed to microorganisms through contact with microorganisms through contact with contaminated instruments or other patient-contaminated instruments or other patient-care items. care items.

Exposure may occur through percutaneous Exposure may occur through percutaneous injury (e.g., needlesticks, cuts) or contact with injury (e.g., needlesticks, cuts) or contact with the mucous membranes of the eyes, nose, or the mucous membranes of the eyes, nose, or mouth.mouth.


Instrument-Processing AreaInstrument-Processing Area

The instrument-processing area, or The instrument-processing area, or sterilization area, should be centrally located sterilization area, should be centrally located in the office to permit easy access from all in the office to permit easy access from all patient-care areas. patient-care areas.

A central location minimizes the need to carry A central location minimizes the need to carry contaminated items through clean areas of contaminated items through clean areas of the office (where sterilized instruments, fresh the office (where sterilized instruments, fresh disposable supplies, and prepared trays are disposable supplies, and prepared trays are stored). stored).



Instrument-Processing AreaInstrument-Processing Area


The ideal instrument-processing area: The ideal instrument-processing area: Should be dedicated only to instrument processingShould be dedicated only to instrument processing Should be physically separated from the Should be physically separated from the

operatories and dental laboratoryoperatories and dental laboratory Should not be a part of a common walkway Should not be a part of a common walkway

The area should not have a door or windows The area should not have a door or windows that open to the outside, because dust may that open to the outside, because dust may enter the area.enter the area.



Instrument Processing AreaInstrument Processing Area


The processing area should have good air The processing area should have good air circulation to control the heat generated by circulation to control the heat generated by the sterilizers.the sterilizers.

The size of the area should accommodate all The size of the area should accommodate all the equipment and supplies necessary for the equipment and supplies necessary for instrument processing, with multiple outlets instrument processing, with multiple outlets and proper lighting, water, and air and and proper lighting, water, and air and vacuum lines for flushing of high-speed vacuum lines for flushing of high-speed handpieces.handpieces.



Instrument Processing AreaInstrument Processing Area


A deep sink should have hands-free controls A deep sink should have hands-free controls for instrument rinsing and (if space permits) a for instrument rinsing and (if space permits) a foot-operated or other hands-free trash foot-operated or other hands-free trash receptacle. receptacle.

The flooring should be an uncarpeted, The flooring should be an uncarpeted, seamless, hard surface. seamless, hard surface.

The size, shape, and accessories of the The size, shape, and accessories of the instrument- processing area vary among instrument- processing area vary among dental offices. dental offices.


Rankings of EvidenceRankings of Evidence


Workflow PatternWorkflow Pattern

Regardless of the size or shape of the instrument-Regardless of the size or shape of the instrument-processing area, four basic areas govern the pattern of processing area, four basic areas govern the pattern of workflow.workflow.

Processing of instruments should proceed in a single loop, Processing of instruments should proceed in a single loop, from dirty to clean to sterile to storage, without ever from dirty to clean to sterile to storage, without ever “doubling back.” “doubling back.”

If the instrument-processing area is small, you can use If the instrument-processing area is small, you can use signs: signs: ““Contaminated items only”Contaminated items only” ““Precleaning area” Precleaning area” ““Cleaned items only” Cleaned items only” ““Sterile items only” Sterile items only” ““Sterilization area”Sterilization area”


Fig. 21-2 A, Linear and B, U-shaped Fig. 21-2 A, Linear and B, U-shaped instrument-processing areas.instrument-processing areas.


Contaminated AreaContaminated Area

All soiled instruments are brought into the contaminated All soiled instruments are brought into the contaminated area, the initial receiving area, where they are held for area, the initial receiving area, where they are held for processing. Any disposable items that have not already processing. Any disposable items that have not already been discarded in the treatment room are removed from the been discarded in the treatment room are removed from the instrument tray and disposed of as contaminated waste.instrument tray and disposed of as contaminated waste.

Thorough cleaning should be done before all disinfection Thorough cleaning should be done before all disinfection and sterilization processes. It should involve the removal of and sterilization processes. It should involve the removal of all debris and organic materials (e.g., blood and saliva).all debris and organic materials (e.g., blood and saliva).

The contaminated area contains clean protective eyewear The contaminated area contains clean protective eyewear and utility gloves, counter space, a sink, a waste-disposal and utility gloves, counter space, a sink, a waste-disposal container, holding solution, an ultrasonic cleaner, an container, holding solution, an ultrasonic cleaner, an eyewash station, and supplies for the wrapping of eyewash station, and supplies for the wrapping of instruments before sterilization. instruments before sterilization.


Fig. 21-3 Waste items are properly discarded.Fig. 21-3 Waste items are properly discarded.


Preparation and Packaging AreaPreparation and Packaging Area

In the area set aside for preparation and In the area set aside for preparation and packaging area, cleaned instruments and packaging area, cleaned instruments and other dental supplies should be inspected, other dental supplies should be inspected, assembled into sets or trays, and wrapped or assembled into sets or trays, and wrapped or placed in packages for sterilization. placed in packages for sterilization.


Fig. 21-4 A modern sterilization center.Fig. 21-4 A modern sterilization center.


Holding SolutionHolding Solution

If a instruments cannot be cleaned immediately after a If a instruments cannot be cleaned immediately after a procedure, they should be placed in a holding solution to procedure, they should be placed in a holding solution to prevent the drying of blood and debris on the instruments.prevent the drying of blood and debris on the instruments.

The holding solution may be any noncorrosive liquid. A The holding solution may be any noncorrosive liquid. A commercial enzymatic solution that partially dissolves commercial enzymatic solution that partially dissolves organic debris may be used. organic debris may be used.

Dishwasher detergent also makes a good holding solution Dishwasher detergent also makes a good holding solution because it is low-cost, low-foaming, and readily available. because it is low-cost, low-foaming, and readily available.

It is neither cost-effective nor desirable to use a It is neither cost-effective nor desirable to use a disinfectant alone as a holding solution.disinfectant alone as a holding solution.



Holding SolutionHolding Solution


The container must have a lid and must be labeled The container must have a lid and must be labeled with both a biohazard label (because of the with both a biohazard label (because of the contaminated instruments) and a chemical label contaminated instruments) and a chemical label (because of the cleaner/detergent). (because of the cleaner/detergent).

The holding solution should be changed at least The holding solution should be changed at least twice daily and even more frequently if it becomes twice daily and even more frequently if it becomes clouded.clouded.

Remember, a holding solution is necessary only Remember, a holding solution is necessary only when contaminated instruments cannot be when contaminated instruments cannot be processed immediately.processed immediately.


Fig. 21-5 Commercial holding solutions are available for use Fig. 21-5 Commercial holding solutions are available for use in precleaning. in precleaning.

(Courtesy of Biotrol International.)(Courtesy of Biotrol International.)


Precleaning and Packaging Precleaning and Packaging InstrumentsInstruments

Instruments may be precleaned in one of Instruments may be precleaned in one of three ways: three ways: Hand scrubbingHand scrubbing Ultrasonic cleaningUltrasonic cleaning Instrument-washing machineInstrument-washing machine


Hand ScrubbingHand Scrubbing

Hand scrubbing is the least desirable method Hand scrubbing is the least desirable method of cleaning instruments because it requires of cleaning instruments because it requires direct hand contact with the contaminated direct hand contact with the contaminated instrument. instrument.


Hand-Scrubbing InstrumentsHand-Scrubbing Instruments

Wear goggle-type eyewear and puncture-resistant Wear goggle-type eyewear and puncture-resistant gloves in addition to your your protective clothing. gloves in addition to your your protective clothing. Clean only one or two instruments at a time.Clean only one or two instruments at a time.

Use only a long-handled brush, preferably one with a Use only a long-handled brush, preferably one with a hand guard or wide surface.hand guard or wide surface.

Keep items above the waterline; fully immersing them Keep items above the waterline; fully immersing them in a basin of soapy water interferes with your ability to in a basin of soapy water interferes with your ability to see the sharp ends.see the sharp ends.

Allow instruments to air-dry or carefully pat them with Allow instruments to air-dry or carefully pat them with thick toweling. To decrease the risk of accidental thick toweling. To decrease the risk of accidental injury, never rub or roll instruments in a towel.injury, never rub or roll instruments in a towel.


Ultrasonic CleaningUltrasonic Cleaning

Ultrasonic cleaners are used to loosen and remove Ultrasonic cleaners are used to loosen and remove debris from instruments. These cleaners also reduce debris from instruments. These cleaners also reduce the risk of cuts and punctures to the hands during the the risk of cuts and punctures to the hands during the cleaning process.cleaning process.

Puncture-resistant utility gloves, a mask, protective Puncture-resistant utility gloves, a mask, protective eyewear, and a protective gown should always be eyewear, and a protective gown should always be worn when the ultrasonic cleaner is being used. worn when the ultrasonic cleaner is being used.

To further limit contact with contaminated To further limit contact with contaminated instruments, keep a set of tongs near the ultrasonic instruments, keep a set of tongs near the ultrasonic unit with which to remove instruments after the unit with which to remove instruments after the cleaning cycle. cleaning cycle.


Fig. 21-6 Ultrasonic cleaning system. A, Ultrasonic cleaner. B, Fig. 21-6 Ultrasonic cleaning system. A, Ultrasonic cleaner. B, Instrument basket. C, Beaker holder. D, Bur tray. E, Suspension Instrument basket. C, Beaker holder. D, Bur tray. E, Suspension

bracket. F, Beaker band. G, Beaker cover. H, Glass beaker. I, Cover. bracket. F, Beaker band. G, Beaker cover. H, Glass beaker. I, Cover.

(Courtesy of L & R Manufacturing Co, Kearny, NJ.)(Courtesy of L & R Manufacturing Co, Kearny, NJ.)


Fig. 21-7 It is important to keep the ultrasonic cleaner Fig. 21-7 It is important to keep the ultrasonic cleaner covered while it is in use to reduce splatter and covered while it is in use to reduce splatter and

contaminated aerosols.contaminated aerosols.


Ultrasonic CleaningUltrasonic Cleaning

The ultrasonic cleaner works by producing sound The ultrasonic cleaner works by producing sound waves beyond the range of human hearing. waves beyond the range of human hearing.

These sound waves, which can travel through metal These sound waves, which can travel through metal and glass containers, cause cavitation (formation of and glass containers, cause cavitation (formation of bubbles in liquid). bubbles in liquid).

Instruments should be processed in the ultrasonic Instruments should be processed in the ultrasonic cleaner until they are visibly clean.cleaner until they are visibly clean.

The time may vary from 5 to 15 minutes, depending The time may vary from 5 to 15 minutes, depending on the amount and type of material on the on the amount and type of material on the instruments and the efficiency of the ultrasonic unit.instruments and the efficiency of the ultrasonic unit.


Ultrasonic Cleaning SolutionsUltrasonic Cleaning Solutions

You should only use ultrasonic solutions that are You should only use ultrasonic solutions that are specially formulated for use in the ultrasonic cleaner.specially formulated for use in the ultrasonic cleaner.

Some ultrasonic cleaning products have enzyme Some ultrasonic cleaning products have enzyme activity.activity.

Other ultrasonic cleaning products have antimicrobial Other ultrasonic cleaning products have antimicrobial activity, which reduces the buildup of microbes in the activity, which reduces the buildup of microbes in the solutions with repeated use. solutions with repeated use.

The antimicrobial activity does not disinfect the The antimicrobial activity does not disinfect the instruments; it merely prevents the microorganisms instruments; it merely prevents the microorganisms from multiplying.from multiplying.



Fig. 21-8 A commercial all-Fig. 21-8 A commercial all-purpose ultrasonic cleaner. purpose ultrasonic cleaner.

(Courtesy of Certol.)(Courtesy of Certol.)

Fig. 21-9 An enzyme ultrasonic cleaner in tablet form.

(Courtesy of Crosstex.)


Ultrasonic Cleaning SolutionsUltrasonic Cleaning Solutions


Do not use other chemicals such as plain disinfectants in Do not use other chemicals such as plain disinfectants in the ultrasonic cleaner. the ultrasonic cleaner.

Some disinfectants can “fix” the blood and debris on the Some disinfectants can “fix” the blood and debris on the instruments, making subsequent cleaning more difficult. instruments, making subsequent cleaning more difficult.

Specific ultrasonic solutions are available for the removal of Specific ultrasonic solutions are available for the removal of difficult materials such as cement, tartar, stains, plaster, difficult materials such as cement, tartar, stains, plaster, and alginate. and alginate.

Refer to the instructions of the ultrasonic unit’s Refer to the instructions of the ultrasonic unit’s manufacturer regarding the specific solution to be used.manufacturer regarding the specific solution to be used.

The ultrasonic cleaning unit should be labeled with both a The ultrasonic cleaning unit should be labeled with both a chemical label and a biohazard label because it contains a chemical label and a biohazard label because it contains a chemical and contaminated instruments.chemical and contaminated instruments.


Care of the Ultrasonic Cleaner Care of the Ultrasonic Cleaner

The ultrasonic cleaning solution is highly The ultrasonic cleaning solution is highly contaminated and must be discarded at least contaminated and must be discarded at least once a day or sooner if it becomes visibly once a day or sooner if it becomes visibly cloudy. cloudy.

When the solution is being changed, the When the solution is being changed, the inside of the pan and lid should be rinsed with inside of the pan and lid should be rinsed with water, disinfected, rinsed again, and dried. water, disinfected, rinsed again, and dried.

All PPE should be worn while solutions are All PPE should be worn while solutions are being changed in the ultrasonic cleaner.being changed in the ultrasonic cleaner.


Testing the Ultrasonic CleanerTesting the Ultrasonic Cleaner

If you notice that the instruments are not being cleaned If you notice that the instruments are not being cleaned completely with processing in the ultrasonic cleaner, the unit completely with processing in the ultrasonic cleaner, the unit may not be functioning properly.may not be functioning properly.

To determine whether the ultrasonic cleaner is working properly, To determine whether the ultrasonic cleaner is working properly, hold a 5-by-5-inch sheet of lightweight aluminum foil vertically hold a 5-by-5-inch sheet of lightweight aluminum foil vertically (like a curtain) half-submerged in fresh, unused solution. (like a curtain) half-submerged in fresh, unused solution.

Run the unit for 20 seconds, then hold the foil up to the light. Run the unit for 20 seconds, then hold the foil up to the light. The surfaces that were submerged in the solution should be The surfaces that were submerged in the solution should be

evenly marked with a tiny pebbling effect over the entire evenly marked with a tiny pebbling effect over the entire surface.surface.

An area without pebbling of more than ½ inch indicates a An area without pebbling of more than ½ inch indicates a problem with the unit, and it needs to be serviced by the problem with the unit, and it needs to be serviced by the manufacturer. manufacturer.


Automated Washers/DisinfectorsAutomated Washers/Disinfectors

Automated instrument washers/disinfectors look and work Automated instrument washers/disinfectors look and work similar to a household dishwasher. similar to a household dishwasher.

However, they must be approved by the U.S. Food and Drug However, they must be approved by the U.S. Food and Drug Administration. Administration.

Automated washing/disinfecting units use a combination of Automated washing/disinfecting units use a combination of very hot recirculating water and detergents to remove organic very hot recirculating water and detergents to remove organic material. material.

After washing, the instruments are automatically dried. These After washing, the instruments are automatically dried. These units are classified as thermal disinfectors because they have units are classified as thermal disinfectors because they have a disinfecting cycle that subjects the instruments to a level of a disinfecting cycle that subjects the instruments to a level of heat that kills most vegetative microorganisms.heat that kills most vegetative microorganisms.

Instruments processed in an automatic washer/disinfector Instruments processed in an automatic washer/disinfector must be wrapped and sterilized before use on a patient.must be wrapped and sterilized before use on a patient.


Drying, Lubrication, and Corrosion Drying, Lubrication, and Corrosion ControlControl

Instruments and burs made of carbon steel will Instruments and burs made of carbon steel will rust during steam sterilization.rust during steam sterilization.

Rust inhibitors such as sodium nitrate and Rust inhibitors such as sodium nitrate and commercial products, which are available as commercial products, which are available as spray and dip solution, can be used to help spray and dip solution, can be used to help reduce rust and corrosion.reduce rust and corrosion.

An alternative to a rust inhibitor is to dry the An alternative to a rust inhibitor is to dry the instrument thoroughly with the use of dry heat instrument thoroughly with the use of dry heat or unsaturated chemical-vapor sterilization or unsaturated chemical-vapor sterilization (discussed later), which does not cause rusting. (discussed later), which does not cause rusting.


Packaging of InstrumentsPackaging of Instruments

Before sterilization, the instruments should be wrapped Before sterilization, the instruments should be wrapped or packaged to protect them from becoming or packaged to protect them from becoming contaminated after sterilization.contaminated after sterilization.

When instruments are sterilized without being When instruments are sterilized without being packaged, they are exposed to the environment as packaged, they are exposed to the environment as soon as the sterilizer door is opened. soon as the sterilizer door is opened.

They can be contaminated by aerosols in the air, dust, They can be contaminated by aerosols in the air, dust, improper handling, or contact with nonsterile surfaces.improper handling, or contact with nonsterile surfaces.

An additional advantage to packaging instruments is An additional advantage to packaging instruments is that they can be grouped into special setups, such as that they can be grouped into special setups, such as crown/bridge, amalgam, prophylactic, or composite.crown/bridge, amalgam, prophylactic, or composite.


Fig. 21-10 Special tartar- and stain-removing Fig. 21-10 Special tartar- and stain-removing ultrasonic solution. ultrasonic solution.

(Courtesy of Crosstex.)(Courtesy of Crosstex.)


Packaging Materials Packaging Materials

Sterilization packaging materials and cassettes are Sterilization packaging materials and cassettes are medical devices and therefore must be FDA-approved. medical devices and therefore must be FDA-approved.

It is of critical importance to use only products and It is of critical importance to use only products and materials that are labeled as “sterilization” packaging.materials that are labeled as “sterilization” packaging.

Never substitute products such as plastic wraps, paper, or Never substitute products such as plastic wraps, paper, or zipper-lock freezer bags that are not registered for this zipper-lock freezer bags that are not registered for this purpose. These products may melt or prevent the purpose. These products may melt or prevent the sterilizing agent from reaching the instruments inside.sterilizing agent from reaching the instruments inside.

Specific types of packaging material are available for each Specific types of packaging material are available for each method of sterilization. You should use only the type of method of sterilization. You should use only the type of packaging material designed for the particular method of packaging material designed for the particular method of sterilization that you are using. sterilization that you are using.



Packaging MaterialsPackaging Materials


A wide variety of sterilization packaging materials are A wide variety of sterilization packaging materials are available. Self-sealing or heat-sealed “poly” bags or available. Self-sealing or heat-sealed “poly” bags or tubes make excellent wraps. tubes make excellent wraps.

Paper and cloth wraps are also available.Paper and cloth wraps are also available. If the package is not the self-sealing type, you should If the package is not the self-sealing type, you should

only use sterilization indicator tape to seal the only use sterilization indicator tape to seal the package.package.

Never use safety pins, staples, paper clips, or other Never use safety pins, staples, paper clips, or other sharp objects that could penetrate the packaging sharp objects that could penetrate the packaging material.material.


Fig. 21-12 Self-seal packages make an excellent wrap for Fig. 21-12 Self-seal packages make an excellent wrap for sterilized materials. sterilized materials.

(Courtesy of SPS Medical Supply Corp.)(Courtesy of SPS Medical Supply Corp.)


Sterilization of Unwrapped Sterilization of Unwrapped InstrumentsInstruments

An unwrapped cycle (sometimes called flash An unwrapped cycle (sometimes called flash sterilization) is a method for sterilizing sterilization) is a method for sterilizing unwrapped patient-care items for immediate unwrapped patient-care items for immediate use. use.

The time for unwrapped sterilization cycles The time for unwrapped sterilization cycles depends on the type of sterilizer and the type depends on the type of sterilizer and the type of item (i.e., porous or nonporous) to be of item (i.e., porous or nonporous) to be sterilized. sterilized.

Unwrapped sterilization should be used only Unwrapped sterilization should be used only under certain conditions. under certain conditions.






Describe the three most common methods of heat Describe the three most common methods of heat sterilization and the advantages and disadvantages sterilization and the advantages and disadvantages of each.of each.

Explain the primary disadvantage of flash Explain the primary disadvantage of flash sterilization.sterilization.

Explain how sterilization failures can occur.Explain how sterilization failures can occur. Explain the limitation of chemical liquid sterilizers.Explain the limitation of chemical liquid sterilizers. Describe the three forms of sterilization monitoring.Describe the three forms of sterilization monitoring. Explain the differences between process indicators Explain the differences between process indicators

and process integrators.and process integrators. Describe when and how biologic monitoring is done.Describe when and how biologic monitoring is done.


Methods of SterilizationMethods of Sterilization

Sterilization destroys all microbial forms, including Sterilization destroys all microbial forms, including bacterial spores. Sterile is an absolute term; there is no bacterial spores. Sterile is an absolute term; there is no “partially sterile” “partially sterile” or “almost sterile.”or “almost sterile.”

All reusable items (critical and semicritical instruments) All reusable items (critical and semicritical instruments) that come into contact with the patient’s blood, saliva, or that come into contact with the patient’s blood, saliva, or mucous membranes must be heat-sterilized. mucous membranes must be heat-sterilized.

The three most common forms of heat sterilization in The three most common forms of heat sterilization in the dental office are the dental office are SteamSteam Chemical vaporChemical vapor Dry heatDry heat


Steam Autoclave Sterilization Steam Autoclave Sterilization

An autoclave is used to sterilize dental instruments An autoclave is used to sterilize dental instruments and other items by means of steam under pressure.and other items by means of steam under pressure.

Steam sterilization involves heating water to generate Steam sterilization involves heating water to generate steam, producing a moist heat that rapidly kills steam, producing a moist heat that rapidly kills microorganisms. microorganisms.

As the steam fills the sterilizing chamber, the cooler As the steam fills the sterilizing chamber, the cooler air is pushed from an escape valve, which then air is pushed from an escape valve, which then closes and allows the pressure to increase. closes and allows the pressure to increase.

It is actually the heat, not the pressure, that kills the It is actually the heat, not the pressure, that kills the microorganisms.microorganisms.



Fig. 21-13 Steam autoclave.Fig. 21-13 Steam autoclave.


Steam Autoclave SterilizationSteam Autoclave Sterilization


Packaging material for steam sterilization must be porous Packaging material for steam sterilization must be porous enough to permit the steam to penetrate to the enough to permit the steam to penetrate to the instruments inside. instruments inside.

The packaging material may be fabric but most often is The packaging material may be fabric but most often is sealed film or paper pouches, nylon tubing, sterilizing sealed film or paper pouches, nylon tubing, sterilizing wrap, or paper-wrapped cassettes.wrap, or paper-wrapped cassettes.

One disadvantage of steam sterilization is that the One disadvantage of steam sterilization is that the moisture may cause corrosion on some high-carbon steel moisture may cause corrosion on some high-carbon steel instruments. instruments.

Distilled water should be used in autoclaves instead of tap Distilled water should be used in autoclaves instead of tap water, which often contains minerals and impurities. water, which often contains minerals and impurities. Distilled water helps minimize corrosion and pitting.Distilled water helps minimize corrosion and pitting.


Autoclave Operation Cycles Autoclave Operation Cycles

Dental-office steam sterilizers usually operate Dental-office steam sterilizers usually operate in four cycles:in four cycles: Heat-upHeat-up SterilizationSterilization DepressurizationDepressurization DryingDrying


Flash SterilizationFlash Sterilization

Rapid or “flash” sterilization of dental instruments is Rapid or “flash” sterilization of dental instruments is accomplished by means of rapid heat transfer, steam, and accomplished by means of rapid heat transfer, steam, and unsaturated chemical vapor.unsaturated chemical vapor.

Flash sterilization may be used only on instruments that are Flash sterilization may be used only on instruments that are placed in the chamber unwrapped. This involves a placed in the chamber unwrapped. This involves a compromise, because the sterility of the instruments is compromise, because the sterility of the instruments is immediately defeated when the instruments are removed immediately defeated when the instruments are removed from the sterilizer.from the sterilizer.

Flash sterilization should also be used only for instruments Flash sterilization should also be used only for instruments that are to be promptly used on removal from the sterilizer. that are to be promptly used on removal from the sterilizer.

It is always the best policy to use a method of sterilization in It is always the best policy to use a method of sterilization in which the instruments can be packaged before use and which the instruments can be packaged before use and remain packaged until the time of use.remain packaged until the time of use.


Fig. 21-15 STAT/M sterilizer. Fig. 21-15 STAT/M sterilizer. (Courtesy of SciScan.)(Courtesy of SciScan.)


Chemical-Vapor SterilizationChemical-Vapor Sterilization

Chemical-vapor sterilization is similar to Chemical-vapor sterilization is similar to autoclaving, except that a combination of autoclaving, except that a combination of chemicals (alcohol, formaldehyde, ketone, chemicals (alcohol, formaldehyde, ketone, acetone, and water) is used instead of water acetone, and water) is used instead of water to create a vapor for sterilization.to create a vapor for sterilization.

OSHA requires a material-safety data sheet, OSHA requires a material-safety data sheet, or MSDS, on the chemical-vapor solution or MSDS, on the chemical-vapor solution because of the chemicals’ toxicity. because of the chemicals’ toxicity.


Advantages of Chemical-Vapor Advantages of Chemical-Vapor SterilizationSterilization

The major advantage of the chemical-vapor The major advantage of the chemical-vapor sterilizer is that it does not rust, dull, or corrode dry sterilizer is that it does not rust, dull, or corrode dry metal instruments. metal instruments.

The low water content of the vapor prevents The low water content of the vapor prevents destruction of items such as endodontic files, destruction of items such as endodontic files, orthodontic pliers, wires, bands, and burs. orthodontic pliers, wires, bands, and burs.

A wide range of items can be sterilized routinely A wide range of items can be sterilized routinely without damage. without damage.

Other advantages include the short cycle time and Other advantages include the short cycle time and the availability of a dry instrument after the cycle. the availability of a dry instrument after the cycle.


Disadvantages of Chemical-Vapor Disadvantages of Chemical-Vapor SterilizationSterilization

The primary disadvantage is that adequate The primary disadvantage is that adequate ventilation is essential because residual ventilation is essential because residual chemical vapors containing formaldehyde and chemical vapors containing formaldehyde and methyl alcohol may be released when the methyl alcohol may be released when the chamber door is opened at the end of the chamber door is opened at the end of the cycle. cycle.

These vapors can temporarily leave an These vapors can temporarily leave an unpleasant odor in the area and may be unpleasant odor in the area and may be irritating to the eyes.irritating to the eyes.


Filtration and Monitoring of Chemical Filtration and Monitoring of Chemical Vapors Vapors

Newer sterilizers are equipped with a special Newer sterilizers are equipped with a special filtration device that further reduces the amount filtration device that further reduces the amount of chemical vapor remaining in the chamber at of chemical vapor remaining in the chamber at the end of the cycle. Older models can usually be the end of the cycle. Older models can usually be retrofitted.retrofitted.

Formaldehyde-monitoring badges, similar to Formaldehyde-monitoring badges, similar to radiation monitoring devices, are available for radiation monitoring devices, are available for employees. The badge measures personal employees. The badge measures personal exposure to formaldehyde for a period and is exposure to formaldehyde for a period and is then mailed to the monitoring service, which then mailed to the monitoring service, which sends a laboratory analysis to the employee.sends a laboratory analysis to the employee.


Packaging for Chemical-Vapor Packaging for Chemical-Vapor SterilizationSterilization

Standard packaging for chemical-vapor sterilization Standard packaging for chemical-vapor sterilization includes film pouches or paper bags, nylon see-through includes film pouches or paper bags, nylon see-through tubing, sterilization wrap, and wrapped cassettes. tubing, sterilization wrap, and wrapped cassettes.

Thick or tightly wrapped items require longer exposure Thick or tightly wrapped items require longer exposure because of the inability of the unsaturated chemical because of the inability of the unsaturated chemical vapors to penetrate as well as saturated chemical vapors to penetrate as well as saturated chemical vapors under pressure do.vapors under pressure do.

As with autoclaving, closed containers (e.g., solid-metal As with autoclaving, closed containers (e.g., solid-metal trays and capped glass vials) and aluminum foil cannot trays and capped glass vials) and aluminum foil cannot be used in a chemical-vapor sterilizer because they be used in a chemical-vapor sterilizer because they prevent the sterilizing agent from reaching the prevent the sterilizing agent from reaching the instruments inside.instruments inside.


Pressure, Temperature, and Duration Pressure, Temperature, and Duration of Chemical-Vapor Sterilizationof Chemical-Vapor Sterilization

The three major factors in chemical-vapor The three major factors in chemical-vapor sterilization are:sterilization are: Pressure, which should measure 20 psi Pressure, which should measure 20 psi Temperature, which should measure Temperature, which should measure

131° C (270° F) 131° C (270° F) Time, which should measure 20 to 40 minutesTime, which should measure 20 to 40 minutes


Dry-Heat SterilizationDry-Heat Sterilization

Dry-heat sterilizers operate by heating up air and Dry-heat sterilizers operate by heating up air and transferring that heat from the air to the instruments.transferring that heat from the air to the instruments.

This form of sterilization requires higher temperatures This form of sterilization requires higher temperatures than does steam or chemical-vapor sterilization.than does steam or chemical-vapor sterilization.

Dry-heat sterilizers operate at approximately 160° to Dry-heat sterilizers operate at approximately 160° to 190° C (320°-375° F), depending on the type of 190° C (320°-375° F), depending on the type of sterilizer.sterilizer.

The advantage of dry heat is that the instruments will The advantage of dry heat is that the instruments will not rust if they are thoroughly dry before being placed not rust if they are thoroughly dry before being placed in the sterilizer.in the sterilizer.

There are two types of dry-heat sterilizers: static-air and There are two types of dry-heat sterilizers: static-air and forced-air.forced-air.


Static-Air Sterilizers Static-Air Sterilizers

The static-air sterilizer is similar to an oven: The heating The static-air sterilizer is similar to an oven: The heating coils are on the bottom of the chamber, and the hot air coils are on the bottom of the chamber, and the hot air rises inside by way of natural convection.rises inside by way of natural convection.

Heat is transferred from the static (nonmoving) air to the Heat is transferred from the static (nonmoving) air to the instruments in 1 to 2 hours. instruments in 1 to 2 hours.

Disadvantages of static dry heat: The sterilization process Disadvantages of static dry heat: The sterilization process is time-consuming, and it may not be effective if the is time-consuming, and it may not be effective if the operator errs in calculating the correct processing time.operator errs in calculating the correct processing time.

The wrapping material must be heat-resistant. Aluminum The wrapping material must be heat-resistant. Aluminum foil, metal, and glass containers may be used. Paper and foil, metal, and glass containers may be used. Paper and cloth packs should be avoided because they may burn or cloth packs should be avoided because they may burn or discolor in the intense heat.discolor in the intense heat.


Forced-Air Sterilizers Forced-Air Sterilizers

The forced-air sterilizer, also called the rapid-The forced-air sterilizer, also called the rapid-heat-transfer sterilizer, circulates the hot air heat-transfer sterilizer, circulates the hot air throughout the chamber at a high velocity. throughout the chamber at a high velocity.

This action permits rapid transfer of heat This action permits rapid transfer of heat energy from the air to the instruments, energy from the air to the instruments, reducing the time needed for sterilization. reducing the time needed for sterilization.

Exposure time in a forced-air sterilizer, after Exposure time in a forced-air sterilizer, after the sterilizing temperature has been reached, the sterilizing temperature has been reached, ranges from 6 minutes for unpackaged items ranges from 6 minutes for unpackaged items to 12 minutes for packaged items.to 12 minutes for packaged items.


Ethylene Oxide SterilizationEthylene Oxide Sterilization

The use of ethylene oxide gas is a recognized method of The use of ethylene oxide gas is a recognized method of sterilization. This method is carried out at low temperatures, sterilization. This method is carried out at low temperatures, which is an advantage for plastic and rubber items that which is an advantage for plastic and rubber items that would melt in heat sterilizers.would melt in heat sterilizers.

However, ethylene oxide sterilization requires 4 to 12 However, ethylene oxide sterilization requires 4 to 12 hours, depending on the sterilizer model, and at least 16 hours, depending on the sterilizer model, and at least 16 hours of poststerilization aeration is required to remove the hours of poststerilization aeration is required to remove the gas molecules bound to plastic and rubber surfaces.gas molecules bound to plastic and rubber surfaces.

Ethylene oxide is ineffective on wet items. Toxicity is Ethylene oxide is ineffective on wet items. Toxicity is possible if the gas is not handled properly.possible if the gas is not handled properly.

Ethylene oxide sterilizing units are often used in large Ethylene oxide sterilizing units are often used in large clinics or hospital settings but are only rarely found in clinics or hospital settings but are only rarely found in private dental practices.private dental practices.


Chemical-Liquid SterilizationChemical-Liquid Sterilization

Not all items can withstand heat sterilization. Some Not all items can withstand heat sterilization. Some types of plastics, such as some rubber dam frames, types of plastics, such as some rubber dam frames, shade guides, and x-ray film–holding devices, are shade guides, and x-ray film–holding devices, are damaged by heat sterilization. damaged by heat sterilization.

A liquid sterilant such as 2.0% to 3.4% glutaraldehyde A liquid sterilant such as 2.0% to 3.4% glutaraldehyde must be used for sterilization of these items.must be used for sterilization of these items.

Sterilization in glutaraldehyde requires 10 hours of Sterilization in glutaraldehyde requires 10 hours of contact time; anything less than 10 hours is contact time; anything less than 10 hours is disinfection, not sterilization.disinfection, not sterilization.

Be sure that you have an MSDS for these products. All Be sure that you have an MSDS for these products. All employees should be properly trained to handle them. employees should be properly trained to handle them.


Fig. 21-17 SPOROX II is a high-level disinfectant/sterilant used Fig. 21-17 SPOROX II is a high-level disinfectant/sterilant used for instruments that cannot tolerate heat sterilization.for instruments that cannot tolerate heat sterilization.

(Courtesy of Sultan Chemists Inc, Englewood, NJ.)(Courtesy of Sultan Chemists Inc, Englewood, NJ.)


Sterilization FailuresSterilization Failures

Sterilization may fail when direct contact for Sterilization may fail when direct contact for the correct time between the sterilizing agent the correct time between the sterilizing agent (chemical or steam) and all surfaces of the (chemical or steam) and all surfaces of the items being processed is insufficient. items being processed is insufficient.

Several factors can cause the sterilization Several factors can cause the sterilization process to fail, including improper instrument process to fail, including improper instrument cleaning or packaging and sterilizer cleaning or packaging and sterilizer malfunction.malfunction.


Table 21-7 Results of Sterilization Errors.Table 21-7 Results of Sterilization Errors.


Sterilization MonitoringSterilization Monitoring

It is critical that dental instruments be properly It is critical that dental instruments be properly sterilized. sterilized. Because microorganisms cannot be seen with the Because microorganisms cannot be seen with the

naked eye, the major difficulty in sterilization is naked eye, the major difficulty in sterilization is determining determining when an item is sterile.when an item is sterile.

Currently, three forms of sterilization monitoring Currently, three forms of sterilization monitoring are used: physical, chemical, and biologic. are used: physical, chemical, and biologic. All three processes are unique, have different All three processes are unique, have different

functions, and must be used consistently to ensure functions, and must be used consistently to ensure sterility.sterility.


Physical MonitoringPhysical Monitoring

Physical monitoring of the sterilization process involves Physical monitoring of the sterilization process involves looking at the gauges and readings on the sterilizer looking at the gauges and readings on the sterilizer and recording temperatures, pressure, and exposure and recording temperatures, pressure, and exposure time. time.

Although correct readings do not guarantee Although correct readings do not guarantee sterilization, an incorrect reading is the first signal of a sterilization, an incorrect reading is the first signal of a problem.problem.

Remember that the reading reflects the temperature in Remember that the reading reflects the temperature in the chamber, not inside the pack. the chamber, not inside the pack.

For this reason, problems with overloading or improper For this reason, problems with overloading or improper packaging would not be revealed by the reading on the packaging would not be revealed by the reading on the gauges.gauges.


Chemical MonitoringChemical Monitoring

Chemical monitoring (external and internal) Chemical monitoring (external and internal) involves the use of a heat-sensitive chemical involves the use of a heat-sensitive chemical that changes color when exposed to certain that changes color when exposed to certain conditions. conditions.

There are two types of chemical indicators: There are two types of chemical indicators: Process indicators Process indicators Process integratorsProcess integrators


Process Indicators Process Indicators

Process indicators (external) are placed outside the Process indicators (external) are placed outside the instrument packages before sterilization. instrument packages before sterilization.

Examples include autoclave tape and color-change Examples include autoclave tape and color-change markings on packages or bags.markings on packages or bags.

Process indicators simply identify instrument packs Process indicators simply identify instrument packs that have been exposed to a certain temperature; that have been exposed to a certain temperature; they do not indicate duration or pressure.they do not indicate duration or pressure.

Process indicators are useful in distinguishing Process indicators are useful in distinguishing between packages that have been processed and between packages that have been processed and those have not.those have not.


Fig. 21-18 A, Unprocessed instruments. B, Wrapped instruments after Fig. 21-18 A, Unprocessed instruments. B, Wrapped instruments after processing. Note the color change in the tape. processing. Note the color change in the tape.

(From Young AP, Kennedy DB: (From Young AP, Kennedy DB: Kinn’s the medical assistant: an applied learning approachKinn’s the medical assistant: an applied learning approach , ed 9, , ed 9, Philadelphia, 2003, Saunders.)Philadelphia, 2003, Saunders.)

A B


Process IntegratorsProcess Integrators

Process integrators (internal) are placed inside Process integrators (internal) are placed inside instrument packages.instrument packages.

They respond to a combination of pressure, They respond to a combination of pressure, temperature, and time. temperature, and time.

Process integrators are also known as Process integrators are also known as multiparameter indicators. All sterilization factors are multiparameter indicators. All sterilization factors are integrated.integrated.

Process indicators and integrators provide immediate Process indicators and integrators provide immediate visual control of sterilizing conditions. visual control of sterilizing conditions.

They do not indicate sterility and are not a They do not indicate sterility and are not a replacement for biologic monitoring.replacement for biologic monitoring.


Biologic MonitoringBiologic Monitoring

Biologic monitoring, or spore testing, is the only way Biologic monitoring, or spore testing, is the only way to determine whether sterilization has occurred and to determine whether sterilization has occurred and all bacteria and endospores have been killed. all bacteria and endospores have been killed.

The CDC, American Dental Association, and Office of The CDC, American Dental Association, and Office of Safety and Asepsis Procedures Research Foundation Safety and Asepsis Procedures Research Foundation recommend at least weekly biologic testing of recommend at least weekly biologic testing of sterilization equipment.sterilization equipment.

Several states also require routine biologic checks at Several states also require routine biologic checks at weekly, monthly, or cycle-specific intervals, such as weekly, monthly, or cycle-specific intervals, such as spore testing every 40 hours of use or every 30 days. spore testing every 40 hours of use or every 30 days.


Biologic IndicatorsBiologic Indicators

Also known as spore tests, biologic indicators (BIs) are vials or Also known as spore tests, biologic indicators (BIs) are vials or strips of paper that contain harmless bacterial spores (which are strips of paper that contain harmless bacterial spores (which are highly resistant highly resistant to heat).to heat).

Three BIs are used in testing. Two BIs are placed inside Three BIs are used in testing. Two BIs are placed inside instrument packs, and the sterilizer is operated under normal instrument packs, and the sterilizer is operated under normal conditions. The third strip is set aside as a control.conditions. The third strip is set aside as a control.

After the load has been sterilized, all BIs are cultured. If the After the load has been sterilized, all BIs are cultured. If the spores survive the sterilization cycle (a positive culture), spores survive the sterilization cycle (a positive culture), sterilization failure has occurred.sterilization failure has occurred.

If the spores are killed (a negative culture), the sterilization cycle If the spores are killed (a negative culture), the sterilization cycle was successful.was successful.

The culturing of the spore test is usually handled with the use of The culturing of the spore test is usually handled with the use of a mail-in monitoring service.a mail-in monitoring service.


Fig. 21-21 Use of a mail-in Fig. 21-21 Use of a mail-in service is a convenient service is a convenient

method of biologic method of biologic monitoring. monitoring.

(Courtesy of SPSmedical Supply Corp.)(Courtesy of SPSmedical Supply Corp.)

Fig. 21-22 In-office biologic Fig. 21-22 In-office biologic monitoring system. monitoring system.

(Courtesy of Certol.)(Courtesy of Certol.)






Describe the steps in cleaning and Describe the steps in cleaning and sterilization of the high-speed dental sterilization of the high-speed dental handpiece.handpiece.


Handpiece SterilizationHandpiece Sterilization

High-speed dental handpieces rotate at High-speed dental handpieces rotate at speeds up to 400,000 revolutions per minute speeds up to 400,000 revolutions per minute (rpm). (rpm).

Blood, saliva, and tooth fragments, as well as Blood, saliva, and tooth fragments, as well as restorative materials, may lodge in the head restorative materials, may lodge in the head of the handpiece, where they may be retained of the handpiece, where they may be retained and transferred to another patient. and transferred to another patient.

Therefore, dental handpieces must be Therefore, dental handpieces must be properly cleaned and heat-sterilized.properly cleaned and heat-sterilized.


Handpiece Flushing TechniquesHandpiece Flushing Techniques

Flushing the handpiece is the best way to remove Flushing the handpiece is the best way to remove debris from the head of the handpiece.debris from the head of the handpiece.

To flush a dental handpiece: To flush a dental handpiece: Attach a pressurized handpiece cleaner to the intake tube of Attach a pressurized handpiece cleaner to the intake tube of

the handpiece (where the air passes through).the handpiece (where the air passes through). Flush the head of the handpiece to remove debris.Flush the head of the handpiece to remove debris. Blow out the handpiece using compressed air to remove Blow out the handpiece using compressed air to remove

debris before sterilization.debris before sterilization. Running coolant water from the dental unit through Running coolant water from the dental unit through

the handpiece at chairside is insufficient. Coolant the handpiece at chairside is insufficient. Coolant water does not run through the turbine chamber, water does not run through the turbine chamber, where debris can collect.where debris can collect.


Handpiece Sterilization TechniquesHandpiece Sterilization Techniques

Only steam sterilization and chemical vapor sterilizers are Only steam sterilization and chemical vapor sterilizers are recommended, because handpiece sterilization recommended, because handpiece sterilization temperatures should not exceed 275° F (135° C). temperatures should not exceed 275° F (135° C).

Unless they will be used immediately after sterilization, Unless they will be used immediately after sterilization, handpieces should be packaged in bags, wraps, or packs handpieces should be packaged in bags, wraps, or packs to protect them from contamination before use.to protect them from contamination before use.

Never run a handpiece “hot” out of the sterilizer, and avoid Never run a handpiece “hot” out of the sterilizer, and avoid rapid cool-downs, such as running the handpiece under rapid cool-downs, such as running the handpiece under cold water. Handpieces use very small metal components; cold water. Handpieces use very small metal components; extreme cold changes stresses the metal.extreme cold changes stresses the metal.

If handpieces need to be cooled quickly after sterilization, If handpieces need to be cooled quickly after sterilization, use an air fan to blow room-temperature air over them. use an air fan to blow room-temperature air over them.


Documents

Principles and Techniques of Instrument Processing and Sterilization Chapter 21 Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights